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Thứ Năm, 28 tháng 11, 2013

Modifying Moods with Brain Ultrasound

Ultrasound vibrations applied to the brain may affect mood, according
to scientists. These new findings could potentially lead to new treatments for
psychological and psychiatric disorders.

University of Arizona (UA; USA;Tucson, USA; www.arizona.edu) researchers have found in a
recent study that ultrasound waves applied to specific areas of the brain
appear able to alter patients’ moods. The discovery has led the scientists to conduct
additional investigations with the hope that this technique could one day be
used to treat disorders such as anxiety and depression.

Dr. Stuart Hameroff, professor emeritus of the UA’s
departments of anesthesiology and psychology and director of the UA’s
Center for Consciousness Studies, is lead author on the first clinical
study of brain ultrasound, which was published May 2013 in the
journal Brain Stimulation. Dr. Hameroff became interested in
applying ultrasound to the human brain when he read about a study by
colleague Dr.Jamie Tyler at the Virginia Polytechnic Institute (Blacksburg, USA; www.vt.edu), who discovered physiologic and behavioral
effects in animals of ultrasound applied to the scalp, with the waves passing through the skull.

Dr. Hameroff knew that ultrasound vibrates in megahertz frequencies
at about 10 million vibrations per second, and that microtubules, protein
structures inside brain neurons tied to mood and consciousness, also resonate
in megahertz frequencies. Dr. Hameroff suggested evaluating ultrasound treatment
for mood on human brains. “I said to my anesthesiology colleagues, ‘we should
try this on chronic pain patient volunteers.’”

His colleagues respectfully suggested he try it on himself,
first, Dr.Hameroff concurred. After 15 seconds with an ultrasound transducer,
a traditional ultrasound imaging device, placed against his head, Dr. Hameroff
felt no effect.

“I put it down and said, ‘well, that’s not going to work,’”
he said. “And then about a minute later I started to feel like I’d had a
martini.”

His mood was elevated for the next hour or two, according to
Dr. Hameroff. Aware that his experience could be a placebo
effect, Dr. Hameroff set out to properly test the treatment with a
clinical trial. Dr.Hameroff and his colleagues applied transcranial ultrasound
to 31 chronic pain patients at the University of Arizona Medical Center-South Campus, in a double-blind study in which neither clinicians
nor study

participant knew if the ultrasound unit had been turned on
or off.

Patients reported improvements in mood for up to 40 minutes
following treatment with brain ultrasound, compared with no difference in mood when the machine was switched off. The researchers
confirmed the patients’ subjective reports of increases in positive mood with a
Visual Analog Mood Scale (VAMS), a standardized objective mood scale frequently
employed in psychologic studies. “Encouraging,” Dr. Hameroff remarked. “We’re referring
to transcranial ultrasound as ‘TUS,’” he added. “Which is also the airport code
for Tucson. This was a pilot study, which showed safety, and some efficacy, for
clinical use of TUS. Because important structures called microtubules in all brain
neurons vibrate in the ultrasound range, and help mediate mood and consciousness,
TUS may benefit a variety of neurological and psychiatric disorders.”

The discovery may provide prospects for a possible range of
new applications of ultrasound in medicine. “We frequently use
ultrasound in the operating room for imaging,” said Dr. Hameroff. “It’s
safe as long as you avoid excessive exposure and heating.”

Harmless at low intensities, the mechanical waves penetrate
the body’s tissues and bones, and an echo effect is used to
generate images of anatomic structures such as organs and blood
vessels and fetuses in the womb. Furthermore, the high-frequency
vibrations of ultrasound, which far exceed the range of human hearing and
are undetectable when passing through the body, may be more
desirable than existing brain stimulation techniques such as
transcranial magnetic stimulation (TMS). Used to treat clinically depressed
patients, TMS can have side effects including what some report as a
disagreeable sensation of magnetic waves moving through the head.

After finding encouraging early findings in chronic pain
patients, Dr. Hameroff and his colleagues set out to discover whether
transcranial ultrasound stimulation could improve mood in a larger group
of healthy volunteer test subjects. Jay Sanguinetti, a doctoral
candidate in the department of psychology and his adviser Dr. John Allen, a UA
distinguished professor of psychology,were fascinated by Dr. hameroff’s conception
of evaluating ultrasound. They conducted a follow-up study of ultrasound on UA
psychology student volunteers, recording vital signs such as heart rate and breath
rate, and narrowed down the optimum treatment to 2 megahertz for 30 seconds as
the most likely to produce a positive mood change in patients.

The investigators then began a double-blind clinical trial
to verify the statistical significance of their findings and to rule
out any possibility of a placebo effect in their patients. Results of the
trials are being analyzed, according to Mr.Sanguinetti. “What we think
is happening is that the ultrasound is making the neurons a little bit more
likely to fire in the parts of the brain involved with mood,” thereby stimulating
the brain’s electrical activity and possibly leading to a change in how
participants feel.

The UA researchers are collaborating with the company
Neurotrek (Los Gatos, CA, USA; http://neurotrek.com), which is developing
a device that potentially could target specific regions of the brain

with ultrasound bursts. The researchers will work with a
prototype of the Neurotrek device to evaluate its effectiveness and potential applications.

Mr. Sanguinetti concluded, “The idea is that this device
will be a wearable unit that noninvasively and safely interfaces with
your brain using ultrasound to regulate neural activity.”